Medical Mystery

04.29.13

Are Ultrasounds Causing Autism in Unborn Babies?

Scientists are uncovering disturbing evidence that those sneak peeks at baby could damage a developing brain.

Toward the end of my first pregnancy, a doctor ordered an “emergency” ultrasound because she believed I was measuring small. She turned to go to her next client before I could talk to her about it, muttering that she suspected “intrauterine growth retardation.”

My husband and I sat in the waiting room, flooded with anxiety. The scan showed the baby was fine. It wasn’t until years later when I started researching and writing about pregnancy that I learned that ultrasound scans have not been shown to be any more effective in predicting intrauterine growth restriction (doctors these days try to avoid using the word retardation) than palpation of the pregnant woman’s abdomen by an experienced clinician.

The same summer my daughter was born, Marsden Wagner, an obstetrician, scientist, and former director of Women’s and Children’s Health at the World Health Organization, wrote: “There is no justification for clinicians using routine ultrasound during pregnancy for the management of IUGR.”

Most women look forward to multiple ultrasounds because they are lulled into the assumption that this technology will catch potentially fatal abnormalities—such as a heart defect—early, so they can be fixed. When doctors tell pregnant women they will only get one or two scans, some are terribly disappointed, feeling that they won’t be able to bond as effectively with the baby or worrying that the doctor won’t know that the baby is growing normally. But one study of 15,151 pregnant women published in the New England Journal of Medicine showed that an ultrasound scan does not improve fetal outcome. The study, which was conducted by a team of six researchers over almost four years, compared pregnant women who received two scans to pregnant women who received scans only when some other medical indication suggested an ultrasound was necessary. The results showed no difference in fetal outcomes.

“This practice-based trial demonstrates that among low-risk pregnant women ultrasound screening does not improve perinatal outcome,” the authors conclude. Even when the ultrasound technology uncovered fetal abnormalities, the fetal survival or death rate was the same in both groups.

What the authors did find, however, was that routine ultrasounds led to more expensive prenatal care, adding more than $1 billion to the cost of caring for pregnant women in America each year.

Another study, of 2,834 pregnant women, published in the Lancet, showed that the babies of the randomly chosen group of 1,415 women who received five ultrasounds (as opposed to the group of 1,419 women who had only one scan at eighteen weeks) were much more likely to experience intrauterine growth restriction, a scary combination of words that means the fetus is not developing normally. Ironically, intrauterine growth restriction is one of the conditions that having multiple ultrasounds is supposed to detect.

Though the American College of Obstetricians and Gynecologists recommends that obstetricians discuss the advantages and disadvantages of having an ultrasound scan with pregnant patients, ACOG does not explicitly recommend the screening. ACOG explains that ultrasound may reduce fetal mortality rates because women who discover they are carrying fetuses that are incompatible with life will often choose abortion, but ACOG also specifies that ultrasound has not been proven to be effective for reducing infant mortality in any other way.

Their policy statement continues: “Screening detects multiple gestations, congenital anomalies, and intrauterine growth restriction, but direct health benefits from having this knowledge currently are unproven. The decision ultimately rests with the physician and patient jointly.”

The authors of the definitive, exhaustive, 1,385-page textbook for obstetricians, Williams Obstetrics, take a similarly conservative stance about ultrasound and do not explicitly recommend it for low-risk pregnancies: “Sonography should be performed only with a valid medical indication,” the authors write, “and with the lowest possible exposure setting to gain necessary information.”

Yet doctors and other birth providers take great exception if low-risk pregnant women refuse to be scanned. In 2004 when Lia Joy Rundle, a mom of three from Mazomanie, Wisconsin, was just a few weeks pregnant with her second child, she changed insurance providers. The new obstetrician reviewed her paperwork. “We might be able to do a quick ultrasound today, if the machine’s available,” she said. “Then you can take a look at your baby.”

Though they were planning to have a 20-week ultrasound, Lia and her husband saw no benefit to doing an early ultrasound and felt there might be some risk. But when they declined the scan, the obstetrician insisted there was no way to get an accurate due date without it. “Look at him, he’s fine,” she scoffed, pointing at their 1-year-old son. “How many ultrasounds did you have with him?”

But as I uncovered when I was researching this book, there is mounting evidence that overexposure to sound waves—or perhaps exposure to sound waves at a critical time during fetal development—is to blame for the astronomic rise in neurological disorders among America’s children.

In 2006, Pasko Rakic, M.D., a neuroscientist at Yale University School of Medicine, found that prenatal exposure to ultrasound waves changed the way the neurons in mice distributed themselves in the brain. Rakic and his team do not fully understand what effect the brain cell migratory alteration might have on brain development and intelligence, but they noticed, rather alarmingly, that a smaller percentage of cells migrated to the upper cortical layers of the mouse brain and a larger percentage to the lower layers and white matter.

At first reluctant to publish these results because they were preliminary and might discourage pregnant women from accepting medically necessary ultrasounds (the mice studies are part of a years-long double-blind experiment that is testing the effects of ultrasound on primate brains), Rakic decided the findings were too significant to ignore and concluded that all nonmedical use of ultrasound on pregnant women should be avoided. “We should be using the same care with ultrasound as with X-rays,” Rakic cautioned.

Manuel Casanova, a neurologist who holds an endowed chair at the University of Louisville in Kentucky, is one medical doctor who is listening. Casanova contends that Rakic’s mice research helps confirm a disturbing hypothesis that he and his colleagues have been testing for the last three years: that ultrasound exposure is the main environmental factor contributing to the exponential rise in autism.

When Casanova began researching autism 15 years ago he discovered that neuroscientists had not been able to isolate the differences between an autistic brain and a normal brain, unlike with Parkinson’s disease or Alzheimer’s, where the damage in the brain has been localized. Casanova realized that in order to understand both the causes and the potential cures for autism, scientists needed first to figure out where in the brain of autistic children damage was occurring.

Since no damage to individual neurons had ever been isolated, Casanova theorized that we might not be examining the brain in the right way. He began looking at the brain as a system instead of isolated parts.

It is these columns of neurons working together, which scientists now call “minicolumns,” that are responsible for higher cognitive functions like facial recognition, joint attention (if I turn my face and look somewhere, a child will turn and look too. Not because I told the child to look, but because the normal human brain is wired to do so), and much more. Joint attention is one of the many qualities that appear to be abnormal in the brains of autistic children. Casanova recognized the imperative of studying the circuitry within the brains of patients with autism and other psychiatric conditions. He and his colleagues found something surprising: brains of autistic patients have a 10 to 12 percent higher number of minicolumns as compared to nonautistic brains.

They also found another anomaly. During the normal formation of the human brain, cells divide in the hollows (ventricles) of the brain and then migrate to the surface (cortex), acquiring a vertical organization into columns. At the same time, other cells migrate tangentially and meet up with the columns. Casanova calls these migrations “a very fine ballet,” and explains that the cells that migrate tangentially have an inhibitory role, acting like a container to keep the cells in the minicolumn from spilling into other parts of the brain. Compared with other animals, even primates, the neurons in the human brain have to travel a much longer distance, and during this long migration there is, unfortunately, ample opportunity for things to go wrong.

Casanova explains: “You know that a shower curtain keeps water inside of the bathtub. If you have a defect in the shower curtain, water will spill out of the tub. If the radial migration is not coupled with the tangential migration of inhibitory cells, then the minicolumns will have a faulty shower curtain of inhibition and information will no longer be kept within the core of the minicolumn, it will be able to suffuse to adjacent minicolumns and have an overall amplification affect. Actually the cortex of autistic individuals is hyperexcitable and they suffer from multifocal seizures. One third of autistic individuals have suffered at least two seizures by the time they reach puberty.”

Translation: As the “minicolumn” brain cells move outward, if the complementary cells that inhibit them don’t keep pace, the information in the minicolumns will suffuse out to surrounding cells, causing a chain reaction that can result in seizures.

Ultrasound waves, Casanova explains, are a form of energy known to deform cell membranes. In fact, in the early 1990s the FDA approved the use of ultrasound to treat bone fractures because ultrasound increases cell division. Some cells in the human body are more sensitive than others.

Among the most sensitive cells? Those stem cells in the brain that divide and migrate.

Casanova’s hypothesis: Prolonged or inappropriate ultrasound exposure may actually trigger these cells to divide, migrate, and form too many minicolumns. They divide when they’re not supposed to and there are no inhibitory cells to contain them.

There are more neurologically damaged children in the United States today than ever before. As of 2007, 5.4 million children (the entire population of Finland) have been diagnosed with attention disorders, and today one in every eighty-eight children in America has been diagnosed with an autism spectrum disorder. Japan, Norway, Iceland, Denmark, Australia, France, Germany, Canada, and the United States are among the industrialized nations that are seeing a huge, troubling, and seemingly inexplicable rise in the numbers of autistic children. These countries are geographically and culturally different. Their vaccine schedules are different. The labor and delivery experience is also different: In Scandinavian countries and Japan many more pregnant women tend to choose unmedicated vaginal births.

But all these countries do have one thing in common: the vast majority of pregnant women are getting regular prenatal care and being exposed to ultrasound in the form of anatomy scans and fetal-heart monitoring. In countries with nationalized health care, where virtually every pregnant woman is exposed to multiple ultrasounds, autism rates are even higher than in the United States.

The ultrasounds done on pregnant women today use sound waves with eight times the intensity used before 1991. This time period roughly coincides with the alarming increase in the incidence of autism within our population. Even more disturbing, the majority of technicians using ultrasound machines (as many as 96 percent) do not understand the safety margins they must adhere to in order to make sure the fetus is not exposed to harm.

As ultrasound equipment gets smaller, less expensive, and more portable, it has also become available—without any regulation—to anyone who knows how to surf the Internet. Want to see or hear your baby? You can buy your own ultrasound machine on Amazon or eBay.